There are many occupant or gravity propelled devices employed for recreational use such as roller skates, skate boards, sleds, skis etc. Some of these devices are also designed to be convertible from a wheeled to a ski or runner supported vehicle, or vice versa. Examples of such devices are illustrated in U.S. Pat. Nos. 4,046,392; 4,116,455 and 3,374,000. The main reason for the convertible feature of the above cited patents is to insure that the device can be used year round regardless of the weather conditions prevailing at the time.
Some of the drawbacks of the prior art devices are; their obvious design for a particular surface i.e. snow or pavement, with the converting structure being an obvious afterthought; their failure to incorporate into their design the choice of a standing or sitting position for the operator; the provision of rudimentary steering mechanisms which are crude and limited in the amount of control afforded, and also particularly suited for only one of the surfaces upon which the device is intended to travel; the use of complex braking systems for the pavement use; the total absence of any brakes for those devices intended for use on snow covered surfaces; and various other defects too numerous to mention.